The present invention relates generally to audio reproduction apparatus having a multichannel audio reproduction function, and more particularly to an improved audio reproduction apparatus which can switch a portion of multichannel power amplifiers provided for a first zone to one or more power amplifiers for a second zone. The present invention also relates to an improved audio reproduction apparatus with the multichannel audio reproduction function which can perform ON/OFF control on output to two groups of speaker output terminals independently of each other.
As a form multichannel audio reproduction system, there have been popularly employed, in recent years, digital surround systems which use audio compression techniques, such as Dolby (registered trademark) Digital, DTS (registered trademark: an acronym for Digital Theater System) and AAC (Advanced Audio Coding) techniques.
Recently, multizone audio reproduction systems have also began into wide use, which are designed to deliver audio signals to a plurality of rooms. Heretofore, in cases where a single audio reproduction apparatus, having the multichannel audio reproduction function, is used to perform ON/OFF control on delivery of audio signals to two zones independently of each other, it has been necessary to secure in advance a portion (one or more but not all) of multichannel power amplifiers provided for a first zone (hereinafter also called “first-zone multichannel power amplifiers”) for use as one or more multichannel power amplifiers for a second zone (hereinafter also called “second-zone multichannel power amplifiers”). Hereinafter, delivery of audio signals to the second zone different from the first zone will be referred to as “Zone-2 audio reproduction”.
FIG. 15 is a block diagram illustrating a setup of a conventional audio reproduction apparatus of a type that performs the multichannel audio reproduction function and Zone-2 audio reproduction function. The audio reproduction apparatus of FIG. 15 is intended mainly for multichannel audio reproduction function. When analog audio signals ALIN and ARIN of two channels are input to input terminals 1—1 and 1-2, an A/D converter 2 converts the input analog audio signals ALIN and ARIN into digital audio signals. The thus-converted digital audio signals are passed to a digital signal processor (hereinafter referred to as a “DSP”) 4, where the audio signals are subjected to sound field processing as may be necessary. However, a further description of the input signals to input terminals 1—1 and 1-2 is omitted because these input signals are not multichannel audio inputs to be processed in accordance with the basic principles of the present invention.
When a digital sound signal DIN, compression-coded by the Dolby Digital, DTS or AAC technique, is supplied via an input terminal 1-3 and selector 3 to the DSP 4, the DSP 4 decompression-decodes the input compression-coded digital sound signal DIN by means of an internal decoder 401, to thereby generate various audio signals, i.e. main left and right signals L and R, rear left and right signals RL and RR, center signal C, rear center signal RC and subwoofer (low frequency) signal LFE.
The main left and right signals L and R and rear left and right signals RL and RR, output from a sound field processing section 402 of the DSP 4, are converted by a D/A converter 5 into analog signals, then passed via corresponding volume controls 6-1, 6-2 and 6-3, 6-4 to power amplifiers 7-1, 7-2 and 7-3, 7-4 for amplification, and then output through speaker terminals 8-1, 8-2 and 8-3, 8-4. Further, the subwoofer signal LFE, output from the sound field processing section 402 of the DSP 4, is converted by the D/A converter 5 into an analog signal, then passed to a corresponding volume control 6-7, and then output through a subwoofer output terminal 11.
When audio reproduction is not to be performed in the second zone, selector switches 9-1 and 9-2 are each caused to connect to a “Z1” (first-zone side) contact. In this case, the center signal C and rear center signal RC, output from the sound field processing section 402 of the DSP 4, are converted by the D/A converter 5 into analog signals, then passed, via corresponding volume controls 6-5 and 6—6 and selector switches 9-1 and 9-2, to power amplifiers 7-5 and 7-6 for amplification, and then output through speaker terminals 8-5 and 8-6, respectively.
When, on the other hand, the Zone-2 audio reproduction function is to be used or performed to deliver audio signals of two channels to the second zone, the selector switches 9-1 and 9-2 are each caused to connect to a Z2 (second-zone side) contact. In this case, analog audio signals Z2L and Z2R input to input terminals 1-4 and 1-5 are passed, via corresponding volume controls 6-8 and 6-9 and selector switches 9-1 and 9-2, to the power amplifiers 7-5 and 7-6 for amplification, and then output through the speaker terminals 8-5 and 8-6, respectively.
FIG. 16 is a plan view showing layout or arrangement of the speakers in the first zone Zone 1 for performing the multichannel audio reproduction and in the second zone Zone 2 for performing the two-channel audio reproduction. When the multichannel audio reproduction is to be performed in the first zone Zone 1, the main left and right signals L, R, rear left and right signals RL, RR, center signal C and rear center signal RC, output from the speaker terminals 8-1, 8-2, 8-3, 8-4, 8-5 and 8-6, are supplied to main speakers SP-L, SP-C, rear speakers SP-RL, SP-RR, center speaker SP-C and rear center speaker SP-RC, respectively. The subwoofer signal LFE, output from the subwoofer output terminal 11, is supplied to a subwoofer SP-SW provided with a built-in amplifier. In FIG. 16, each reference character U represents a test-listening position.
When, on the other hand, audio signals of two channels are to be delivered to the second zone for two-channel audio reproduction in the second zone, the audio signals Z2L and Z2R of the two channels, output from the speaker terminals 8-5 and 8-6, are supplied to the speakers SP-Z2L and SP-Z2R, respectively.
In the audio reproduction apparatus of FIG. 15, where the amplifiers 7-5 and 7-6 and speakers 8-5 and 8-6 are shared between the multichannel audio reproduction function and the Zone-2 audio reproduction function, if there is a likelihood of the Zone-2 audio reproduction function being used, it is necessary to previously connect the speakers SP-Z2L and SP-Z2R of the second zone Zone 2 with the speaker terminals 8-5 and 8-6 and connect each of the selector switches 9-1 and 9-2 to the Z2 contact, irrespective of whether or not the Zone-2 audio reproduction function is actually used in the second zone Zone 2. Therefore, even where the center speaker SP-C and rear center speaker SP-RC are positioned in the first zone Zone 1, the center and rear center signals C and RC are not supplied to these center and rear center speakers SP-C and SP-RC.
Namely, when the Zone-2 audio reproduction function is to be performed in the conventional audio reproduction apparatus having the multichannel audio reproduction function and if there can not be provided a specific number of power amplifiers corresponding to a necessary number of channels for the first zone Zone 1 plus a necessary number of channels for the second zone Zone 2, there arises a need to secure in advance a portion of the first-zone multichannel power amplifiers for use as one or more second-zone multichannel power amplifiers. Thus, the number of output channels of the first zone would come short, which would undesirably result in an insufficient multichannel audio reproduction effect in the first zone.
Recently, another type of multizone audio reproduction system has also become popular which are designed to deliver audio signals to a plurality of rooms using a single amplifier. In applications where the multizone audio reproduction function is to be performed using an audio reproduction apparatus, it has been known to provide an A group of main speakers in a first zone and a B group of main speakers in a second zone, and perform, via a main speaker changing switch of the audio reproduction apparatus, ON/OFF control on output to the A-group main speakers and output to the B-group main speakers independently of each other.
FIG. 26 is a block diagram illustrating a setup of such a conventional audio reproduction apparatus. When analog audio signals ALIN and ARIN of two channels are input to input terminals 1—1 and 1-2, an A/D converter 22 converts the input analog audio signals ALIN and ARIN into digital audio signals. The thus-converted digital audio signals are passed to a digital signal processor (DSP) 3, where the audio signals are subjected to sound field processing as may be necessary. When a digital sound signal DIN, compression-coded by the Dolby Digital, DTS or AAC technique, is input to an input terminal 1-3, the DSP 3 decompression-decodes the input compression-coded digital sound signal DIN by means of an internal decoder (not shown), to thereby generate various analog audio signals, i.e. main left and right signals L and R, rear left and right signals RL and RR, center signal C and subwoofer (low frequency) signal LFE.
When the DSP 3 is set in an OFF (or downmix) state (for two-channel audio reproduction), the main left and right signals L and R are output from the DSP 3, but, when the DSP 3 is set in an ON state (for multichannel audio reproduction), the main left and right signals L and R, rear left and right signals RL and RR, center signal C and subwoofer (low frequency) signal LFE are output from the DSP 3.
When audio reproduction is to be performed in the first zone, main speaker changing switches 16-1 and 16-2 are turned on. Thus, the main left and right signals L and R are amplified by power amplifiers 14-1 and 14-2, respectively, and then passed through the main speaker changing switches 16-1 and 16-2 to speaker output terminals 5-1 and 5-2 to be output therefrom. When multichannel audio reproduction is to be performed, the rear left and right signals RL, RR and center signal C, output from the DSP 3, are amplified by power amplifiers 14-3, 14-4 and 14-5, respectively, and then output from speaker output terminals 5-3, 5-4 and 5—5. Further, the subwoofer signal LFE output from the DSP 3 is output from a subwoofer output terminal 17. On the other hand, when audio signals are to be delivered to the second zone, main speaker changing switches 16-3 and 16-4 are turned on. Thus, the main left and right signals L and R, output from the DSP 3, are amplified by the power amplifiers 14-1 and 14-2, respectively, and then passed through the main speaker changing switches 16-3 and 16-4 to speaker output terminals 5-6 and 5-7 to be output therefrom.
FIG. 27 is a plan view showing layout or arrangement of the speakers in the first zone ZoneA capable of the multichannel audio reproduction and the speakers in the second zone ZoneB capable of the two-channel audio reproduction in the conventional audio reproduction apparatus of FIG. 20. In the figure, test-listening positions are each represented by reference character U. When the multichannel audio reproduction is to be performed in the first zone ZoneA, the main left and right signals L, R, rear left and right signals RL, RR and center signal C, output from the speaker terminals 5-1, 5-2, 5-3, 5-4 and 5—5, are supplied to main speakers SP-AL, SP-AR, rear speakers SP-RL, SP-RR and center speaker SP-C, respectively. The subwoofer signal LFE, output from the subwoofer output terminal 17, is supplied to a subwoofer SP-SW provided with a built-in amplifier. When, on the other hand, the audio signals of the two channels are to be delivered to the second zone ZoneB, the audio signals output from the speaker terminals 5-6 and 5-7 are supplied to the speakers SP-BL and SP-BR, respectively.
Namely, the conventional audio reproduction apparatus of FIG. 20 are constructed in such a manner that the output to the main speakers SP-AL and SP-AR of group A and the output to the main speakers SP-BL and SP-BR of group B can be subjected to ON/OFF control independently of each other; however, the conventional audio reproduction apparatus of FIG. 20 is constructed with no consideration as to whether the B-group speakers SP-BL and SP-BR are positioned in the first zone ZoneA or in the second zone ZoneB. Therefore, once the output to the A-group speakers SP-AL and SP-AR is turned off while the multichannel audio reproduction is being executed with the DSP 3 set in the ON state under the environment where the A-group speakers SP-AL and SP-AR are provided in the first zone ZoneA while the B-group speakers SP-BL and SP-BR are provided in the second zone ZoneB, there would arise a problem that only surround signals are reproduced in the first zone ZoneA. Another problem with the conventional audio reproduction apparatus of FIG. 20 is that, if the B-group speakers SP-BL and SP-BR are provided in the second zone ZoneB, no surround signal can be reproduced in the second zone ZoneB and thus no multichannel audio reproduction effect can be achieved in the second zone ZoneB.